The objectives of this application will be to define energy metabolism in the developing lung and to establish relationships between oxidative metabolism and lung phospholipid synthesis. We will also examine pulmonary phospholipid synthesis in fetuses and newborns of diabetic rabbits and as influenced by maternally administered thyrotropin releasing hormone (TRH). We will investigate anaerobic and aerobic glucose metabolism, pentose phosphate pathway activity and fatty acid oxidation at different developmental ages and will determine the influences of changes in oxygen environment and nutritional state on pulmonary oxidative metabolism and phospholipid synthesis. We will utilize lung slices, isolated lung mitochondria, lung subcellular fractions and isolated Type II cells for assay of specific pathways. These data will be correlated with effects on phospholipid synthesis and release obtained using lung slice and lavage techniques. In studies of lung metabolism and phospholipid synthesis in the pregnant diabetic rabbit we will investigate phospholipid synthesis and release using lung slice and lavage techniques. This will be correlated with changes in lung glycogen metabolism and substrate oxidations and interactions. We will also attempt to define the mechanism by which thyrotropin releasing hormone stimulates lung phospholipid synthesis. There is virtually no information available concerning energy metabolism in developing lung. Since lung oxidative metabolism may be central to functional maturation and growth, these studies as well as those of endocrine influences on lung maturation will hopefully provide clues concerning hyaline membrane diseases in the premature infant and in infants of diabetic mothers.